Remove dictionary cache support for simple-cache-middleware

- Remove dictionary cache support altogether, for simple cache middleware, in favor of using the ``SimpleCache`` class.
- Handle missing keys in ``SimpleCache`` a bit more gracefully than throwing a ``KeyError``, just return ``None`` if the key is not in the cache.

docs/web3.utils.rst

@@ -3,7 +3,7 @@ Utils
 
 .. py:module:: web3.utils
 
-The ``utils`` module houses public utility and helper functions.
+The ``utils`` module houses public utility functions and classes.
 
 ABI
 ---
@@ -18,6 +18,16 @@ ABI
     Return the ``output`` names an ABI function or event.
 
 
+Caching
+-------
+
+.. py:class:: Utils.SimpleCache
+
+    The main internal cache class being used internally by web3.py. In some cases, it
+    may prove useful to set your own cache size and pass in your own instance of this
+    class where supported.
+
+
 Exception Handling
 ------------------
 

tests/core/middleware/test_simple_cache_middleware.py

@@ -5,7 +5,6 @@
 
 from web3 import Web3
 from web3._utils.caching import (
-    SimpleCache,
     generate_cache_key,
 )
 from web3.middleware import (
@@ -29,6 +28,9 @@
 from web3.types import (
     RPCEndpoint,
 )
+from web3.utils.caching import (
+    SimpleCache,
+)
 
 
 @pytest.fixture
@@ -52,17 +54,7 @@ def w3(w3_base, result_generator_middleware):
     return w3_base
 
 
-def dict_cache_class_return_value_a():
-    # test dictionary-based cache
-    return {
-        generate_cache_key(f"{threading.get_ident()}:{('fake_endpoint', [1])}"): {
-            "result": "value-a"
-        },
-    }
-
-
-def simple_cache_class_return_value_a():
-    # test `SimpleCache` class cache
+def simple_cache_return_value_a():
     _cache = SimpleCache()
     _cache.cache(
         generate_cache_key(f"{threading.get_ident()}:{('fake_endpoint', [1])}"),
@@ -71,30 +63,20 @@ def simple_cache_class_return_value_a():
     return _cache
 
 
-@pytest.mark.parametrize(
-    "cache_class",
-    (
-        dict_cache_class_return_value_a,
-        simple_cache_class_return_value_a,
-    ),
-)
-def test_simple_cache_middleware_pulls_from_cache(w3, cache_class):
-
+def test_simple_cache_middleware_pulls_from_cache(w3):
     w3.middleware_onion.add(
         construct_simple_cache_middleware(
-            cache_class=cache_class,
+            cache=simple_cache_return_value_a(),
             rpc_whitelist={RPCEndpoint("fake_endpoint")},
         )
     )
 
     assert w3.manager.request_blocking("fake_endpoint", [1]) == "value-a"
 
 
-@pytest.mark.parametrize("cache_class", (dict, SimpleCache))
-def test_simple_cache_middleware_populates_cache(w3, cache_class):
+def test_simple_cache_middleware_populates_cache(w3):
     w3.middleware_onion.add(
         construct_simple_cache_middleware(
-            cache_class=cache_class,
             rpc_whitelist={RPCEndpoint("fake_endpoint")},
         )
     )
@@ -105,8 +87,7 @@ def test_simple_cache_middleware_populates_cache(w3, cache_class):
     assert w3.manager.request_blocking("fake_endpoint", [1]) != result
 
 
-@pytest.mark.parametrize("cache_class", (dict, SimpleCache))
-def test_simple_cache_middleware_does_not_cache_none_responses(w3_base, cache_class):
+def test_simple_cache_middleware_does_not_cache_none_responses(w3_base):
     counter = itertools.count()
     w3 = w3_base
 
@@ -124,7 +105,6 @@ def result_cb(_method, _params):
 
     w3.middleware_onion.add(
         construct_simple_cache_middleware(
-            cache_class=cache_class,
             rpc_whitelist={RPCEndpoint("fake_endpoint")},
         )
     )
@@ -135,8 +115,7 @@ def result_cb(_method, _params):
     assert next(counter) == 2
 
 
-@pytest.mark.parametrize("cache_class", (dict, SimpleCache))
-def test_simple_cache_middleware_does_not_cache_error_responses(w3_base, cache_class):
+def test_simple_cache_middleware_does_not_cache_error_responses(w3_base):
     w3 = w3_base
     w3.middleware_onion.add(
         construct_error_generator_middleware(
@@ -148,7 +127,6 @@ def test_simple_cache_middleware_does_not_cache_error_responses(w3_base, cache_c
 
     w3.middleware_onion.add(
         construct_simple_cache_middleware(
-            cache_class=cache_class,
             rpc_whitelist={RPCEndpoint("fake_endpoint")},
         )
     )
@@ -161,14 +139,9 @@ def test_simple_cache_middleware_does_not_cache_error_responses(w3_base, cache_c
     assert str(err_a) != str(err_b)
 
 
-@pytest.mark.parametrize("cache_class", (dict, SimpleCache))
-def test_simple_cache_middleware_does_not_cache_endpoints_not_in_whitelist(
-    w3,
-    cache_class,
-):
+def test_simple_cache_middleware_does_not_cache_endpoints_not_in_whitelist(w3):
     w3.middleware_onion.add(
         construct_simple_cache_middleware(
-            cache_class=cache_class,
             rpc_whitelist={RPCEndpoint("fake_endpoint")},
         )
     )
@@ -184,7 +157,6 @@ def test_simple_cache_middleware_does_not_cache_endpoints_not_in_whitelist(
 
 async def _async_simple_cache_middleware_for_testing(make_request, async_w3):
     middleware = await async_construct_simple_cache_middleware(
-        cache_class=SimpleCache,
         rpc_whitelist={RPCEndpoint("fake_endpoint")},
     )
     return await middleware(make_request, async_w3)
@@ -201,17 +173,10 @@ def async_w3():
 
 
 @pytest.mark.asyncio
-@pytest.mark.parametrize(
-    "cache_class",
-    (
-        dict_cache_class_return_value_a,
-        simple_cache_class_return_value_a,
-    ),
-)
-async def test_async_simple_cache_middleware_pulls_from_cache(async_w3, cache_class):
+async def test_async_simple_cache_middleware_pulls_from_cache(async_w3):
     async def _properly_awaited_middleware(make_request, _async_w3):
         middleware = await async_construct_simple_cache_middleware(
-            cache_class=cache_class,
+            cache=simple_cache_return_value_a(),
             rpc_whitelist={RPCEndpoint("fake_endpoint")},
         )
         return await middleware(make_request, _async_w3)

tests/core/utilities/test_request.py

@@ -25,13 +25,15 @@
     request,
 )
 from web3._utils.caching import (
-    SimpleCache,
     generate_cache_key,
 )
 from web3._utils.request import (
     cache_and_return_async_session,
     cache_and_return_session,
 )
+from web3.utils.caching import (
+    SimpleCache,
+)
 
 
 class MockedResponse:
@@ -149,10 +151,9 @@ def test_cache_session_class():
     assert "1" not in cache
     assert "1" in evicted_items
 
-    with pytest.raises(KeyError):
-        # This should throw a KeyError since the cache size was 2 and 3 were inserted
-        # the first inserted cached item was removed and returned in evicted items
-        cache.get_cache_entry("1")
+    # Cache size is `3`. We should have "2" and "3" in the cache and "1" should have
+    # been evicted.
+    assert cache.get_cache_entry("1") is None
 
     # clear cache
     request._session_cache.clear()

web3/_utils/caching.py

@@ -1,12 +1,7 @@
 import collections
-from collections import (
-    OrderedDict,
-)
 import hashlib
 from typing import (
     Any,
-    Dict,
-    Union,
 )
 
 from eth_utils import (
@@ -39,66 +34,3 @@ def generate_cache_key(value: Any) -> str:
         raise TypeError(
             f"Cannot generate cache key for value {value} of type {type(value)}"
         )
-
-
-class SimpleCache:
-    def __init__(self, size: int = 100):
-        self._size = size
-        self._data: OrderedDict[str, Any] = OrderedDict()
-
-    def cache(self, key: str, value: Any) -> Dict[str, Any]:
-        evicted_items = None
-        # If the key is already in the OrderedDict just update it
-        # and don't evict any values. Ideally, we could still check to see
-        # if there are too many items in the OrderedDict but that may rearrange
-        # the order it should be unlikely that the size could grow over the limit
-        if key not in self._data:
-            while len(self._data) >= self._size:
-                if evicted_items is None:
-                    evicted_items = {}
-                k, v = self._data.popitem(last=False)
-                evicted_items[k] = v
-        self._data[key] = value
-        return evicted_items
-
-    def get_cache_entry(self, key: str) -> Any:
-        return self._data[key]
-
-    def clear(self) -> None:
-        self._data.clear()
-
-    def items(self) -> Dict[str, Any]:
-        return self._data
-
-    def __contains__(self, item: str) -> bool:
-        return item in self._data
-
-    def __len__(self) -> int:
-        return len(self._data)
-
-
-def type_aware_cache_entry(
-    cache: Union[Dict[str, Any], SimpleCache], cache_key: str, value: Any
-) -> None:
-    """
-    Commit an entry to a dictionary-based cache or to a `SimpleCache` class.
-    """
-    if isinstance(cache, SimpleCache):
-        cache.cache(cache_key, value)
-    else:
-        cache[cache_key] = value
-
-
-def type_aware_get_cache_entry(
-    cache: Union[Dict[str, Any], SimpleCache],
-    cache_key: str,
-) -> Any:
-    """
-    Get a cache entry, with `cache_key`, from a dictionary-based cache or a
-    `SimpleCache` class.
-    """
-    if isinstance(cache, SimpleCache) and cache_key in cache.items():
-        return cache.get_cache_entry(cache_key)
-    elif isinstance(cache, dict) and cache_key in cache:
-        return cache[cache_key]
-    return None

web3/_utils/request.py

@@ -27,9 +27,11 @@
     async_lock,
 )
 from web3._utils.caching import (
-    SimpleCache,
     generate_cache_key,
 )
+from web3.utils.caching import (
+    SimpleCache,
+)
 
 logger = logging.getLogger(__name__)
 
@@ -40,7 +42,7 @@ def get_default_http_endpoint() -> URI:
     return URI(os.environ.get("WEB3_HTTP_PROVIDER_URI", "http://localhost:8545"))
 
 
-_session_cache = SimpleCache(size=100)
+_session_cache = SimpleCache()
 _session_cache_lock = threading.Lock()
 
 
@@ -111,7 +113,7 @@ def _close_evicted_sessions(evicted_sessions: List[requests.Session]) -> None:
 # --- async --- #
 
 
-_async_session_cache = SimpleCache(size=100)
+_async_session_cache = SimpleCache()
 _async_session_cache_lock = threading.Lock()
 _async_session_pool = ThreadPoolExecutor(max_workers=1)